work lost in shafting varies greatly, the limits being 25 to 50%
of the power given; but one should distinguish between instan-
taneous efficiency and that averaged over, say, a whole day.
An extreme case of loss is recorded in Fig. 828, which shews
the H.P. curve of an American workshop during one day.
Neglecting engine friction,
Best results for shafting = 43% 57%
Average results = 36% 64%
The highest H.P. given to shafting and machines was 44, and
the average 39. The machines were next driven by electric
motors, with the result shewn, the highest H.P. given to dynamos,
motors, and machines being reduced to 29 and the average to 21.
Neglecting the engine loss, as before,
Best results for electric driving = 64% 36%
Average results = 62% 38%